Board-mounted electrical connectors comprise a molded non-conductive housing having electrically conductive terminals therein. The housing includes a board mounting face for mounting on a circuit board and a mating face for mating with another connector. The mating face typically is either parallel to the board mounting face or orthogonal thereto. Each terminal in the prior art connector includes a mating end disposed in proximity to the mating face of the housing for achieving electrical connection with a corresponding terminal in a housing mated therewith. Each terminal further includes a board mounting end which extends beyond the board mounting face of the connector for soldered electrical connection to circuitry printed or otherwise disposed on the board.
The housing of the prior art electrical connector must be securely retained on the circuit board prior to soldering of the electrical connections to the board. A connector that is insecurely mounted to the circuit board prior to soldering of the electrical connections may move in response to forces generated during component assembly and soldering operations and may result in improper alignment of the connector with the board. Improper alignment could preclude matability with the connector. Additionally, even after soldering excessive forces generated by the mating and unmating of the improperly positioned connectors may cause movement between the connector and the board. Any such movement between the connector and the circuit board can damage the soldered electrical connections between the terminals and the circuitry on the board. To prevent such movement, the prior art connectors are provided with separate board mounting means which typically are defined by deflectable latches dimensioned and disposed to pass through apertures in the circuit board and to engage regions of the circuit board adjacent to the aperture. In many prior art connectors the board mounting latches are made of plastic and are unitarily molded as part of the electrical connector housing. Each such latch will extend beyond the board mounting face of the electrical connector housing, and will include a ramped leading face to generate deflection during mounting on the circuit board and a locking shoulder for engaging the surface of the circuit board opposite connector. Unitarily molded plastic board mounting latches are widely employed and generally function well. The resiliency inherent in the plastic enables these prior art board mounting means to be deflected several times. However, small plastic board mounting latches may not provide adequate strength for some applications, and can break in response to some applied forces.
Electrical connectors employed in telecommunications equipment, computers and other such devices are subject to generating or picking up radio frequency or electromagnetic interference. Interference of this type can degrade the quality of the signal being carried by the electrical connector or can affect the performance of adjacent connectors. To prevent such interference, many connectors employed in telecommunications equipment and in computers are provided with conductive shielding that is electrically connected to a ground circuit on the circuit board. Some prior art electrical connectors have incorporated the shield and grounding structures of the connector with the board mounting structures. In particular, metallic board mounting means may be employed in place of the above described plastic latches. The metallic board mounting latches may be electrically connected to the shield on the connector and may further be electrically connected to the ground circuit on the circuit board. Metallic board mounting latches can also be engineered to provide exceptional strength, and are less likely to break than plastic latches when subjected to higher then normal forces during mounting of the connector on to the circuit board. In this regard, higher than normal forces may be encountered in situations where the mounting apertures in the circuit board are imprecisely dimensioned or located.
Although metallic board mounting latches provide many advantages as compared to plastic latches, the metallic board mounting structures may exhibit less resiliency than their plastic counterparts. In particular, a plastic latch will tend to return to its initial position after several deflections while the small metallic latches may permanently deform after its first deflection.
One prior art metallic means for mounting an electrical connector to a circuit board is shown in U.S. Pat. No. 4,842,552 which issued to Frantz on Jun. 27, 1989. The mounting member shown in U.S. Pat. No. 4,842,552 includes a formed rectangular body having a pair of opposed flanges extending upwardly and outwardly therefrom for engaging a top surface of the connector and two opposed pairs of locking legs extending downwardly from the body. The legs are configured and dimensioned to pass through a mounting aperture in the electrical connector. The legs will then further extend downwardly through a mounting aperture in the circuit board. Each pair of legs are of slightly different lengths to accommodate variations in board thickness. Thus, depending upon the thickness of the circuit board two legs of the board lock are intended to engage the lower surface of the circuit board. The board lock configuration shown in U.S. Pat. No. 4,842,552 inherently requires a first deflection of all legs as the legs are passed through the mounting aperture in the electrical connector and then a second deflection of all legs as the legs are passed through the mounting aperture in the circuit board. As explained above, the deflection caused by the initial downward movement of the board lock through the aperture in the connector can cause a permanent set in the legs that will diminish the ability of the board lock to securely hold the electrical connector on the circuit board. As explained above, a poorly held circuit board can shift in response to mating forces, vibrations or various environmental conditions, with a resulting potential for damage to soldered electrical connections. Similar board locks having deflectable legs that must be urged downwardly through both the electrical connector and the circuit board are shown in U.S. Pat. No. 4,717,219 which issued to Frantz et al on Jan. 5, 1988 and in U.S. Pat. No. 4,865,555 which issued to Assini et al on Sep. 12, 1989.
U.S. Pat. No. 4,824,398 issued to Taylor on Apr. 25, 1989 and shows a stand-off board lock having a pair of generally semi-cylindrical members intended to pass into and partly through a mounting aperture in a circuit board. A cylindrical stand-off extends between the circuit board and the electrical connector. A smaller cylindrical portion extends axially from the end of the stand-off opposite the circuit board and is dimensioned to pass through apertures in the connector. The stand-off board lock shown in U.S. Pat. No. 4,824,398 is a machined member having a threaded central aperture extending therethrough. A bolt or screw would be passed through the aperture in the electrical connector for threaded engagement with the array of internal threads on the standoff. The machined stand-off board lock shown in U.S. Pat. No. 4,824,398 would be much more expensive to manufacture then stamped and formed components. In this regard, it must be noted that the electrical connector industry is very competitive and even small savings in material and costs can be significant. The requirement of an additional threaded retention member to engage the stand-off further adds to cost and complicates assembly.
Rivets have also been employed as board locks, as shown in U.S. Pat. No. 4,679,883. The rivets shown in U.S. Pat. No. 4,679,883 include a flange at one end to engage either a surface of the circuit board or a surface of the connector. A cylindrical portion extends from the flange and is dimensioned to extend through and beyond both the connector and the circuit board. The end of the cylindrical portion remote from the flange is subsequently mechanically deformed to retain the connector on the circuit board. The forces required to deform a cylindrical portion of a rivet can be undesirably high and can damage portions of the connector. Additionally, rivets are inherently relatively fixed with respect to the disposition of the holes in the connector. Unfortunately, however, considerable variation is likely in the disposition of the mounting apertures in the circuit board. This can require forcing the rivets into the mounting apertures in the circuit board, thereby damaging the circuit board or imposing undesirable stresses thereon.
In view of the above, it is an object of the subject invention to provide a metallic member for mounting an electrical connector to a circuit board.
It is another object of the subject invention to provide a metallic member for mechanically mounting and electrically grounding a connector to a circuit board.
An additional object of the subject invention is to provide an electrical connector having deflectable board engaging latches that do not require an initial deflection prior to mounting on the circuit board.
Yet another object of the subject invention is to provide a board mounting member which ensures secure connector to board engagement despite variations in locations of the board mounting apertures in the board.